Transit through LA - recent reports please

In 3 weeks time we will be transiting through LA on our first return trip to the UK. I want to know what its really like as we've always heard such horror stories about transiting through the US.

We land at 2.45pm (local time) and leave again at 4.45pm (local time).
We are travelling Premium Economy with Air NZ
We will be travelling on our brand, spanky new Kiwi passports and yes we know we will need visas.

What sort of access to space to walk around is there? Is there access to any shops or food retailers? What sort of immigration checks (if any) will we need to go through and how long do they take? Do we have to do anything with our checked in luggage?

I'd be really interested to hear from anyone who has recently (like in the last couple of months) transitted through LA.

My other half has been back and forth via NZ1/2 quite a few times recently and it is actually his preferred route. (he says the planes are nicer and he always travels with Air NZ).
First of all, if you are on a return visit to the UK I assume you have UK passports so the general etiquette of dual nationality is to enter a country with that country's passport, so I would suggest using your NZ passport to leave and enter NZ and your UK ones to enter and leave the UK. Much less hassle at immigration, smaller queues (usually) and less bureaucracy.
As for LA immigration checks, use the same one as you checked in for that leg at the airline with.
Transit via LA is absolutely fine. OK, there are no shops or spending opportunities but it is maximum 2 hours and if you are travelling Premium Economy, needing to purchase food will not be an issue. If you are partaking of all the hospitality on offer with Air NZ, LA will just be a blur anyway. (advice from the frequent flyer though would be to indulge on first leg, abstain on second to minimise jet lag and feeling rubbish when you get there).
All you need for immigration at LA is the ESTA visa which you get online. They check your passport, give you a nice stamp in your passport as a souvenir of your 2 hours in America, take your fingerprints and wish you a nice day.
The LA stop is merely an opportunity for the plane to be refuelled and for a change of crew. They get it over with as quickly as possible and then you are on your way. Your checked-in luggage just stays on the plane, no need to worry about that. Yes, you can walk around (in a small space, but compared to the plane, it's huge) and there is wi-fi.

And as for the horror stories about UK immigration recently, the OH arrived in London the week before the Olympics and he got through UK immigration in about 5 minutes, no queues.

What sort of access to space to walk around is there? Is there access to any shops or food retailers? What sort of immigration checks (if any) will we need to go through and how long do they take? Do we have to do anything with our checked in luggage?

2 hour transit time is very short and I doubt you'll be able to do much venturing. Normally with such a short stop in transit, you get off the plane and go into a holding area, then re-queue back on the plane (or another plane nearby). I'm not even sure if the 2 hours is enough time to get everyone off the plane to go through US Border Protection & Homeland Security. The finger print scan and photo does take more time.

There's a fee for the online ESTA registration - to some, they view it as an inconvenience for only stopping in the US in transit. Fill out arrival declaration cards, etc.

I haven't traveled via LA for 2 years and avoid it like the plague! Queuing up for ages to pass through immigration is a drag and no showers to freshen up. I try to go via Hong Kong-short turn around and access to great facilities. Maybe it's changed recently?

We went through less than two years ago. I'm glad you're travelling PE as at least you'll be off the plane and processed quickly. There's no shopping as it's more of a "holding pen" scenario and they don't want to "lose" people in retail or eating/drinking!

We were business so had the benefit of refreshments in the transit lounge, but I'm not sure what the normal lounge offers. But as girlwithanewf says, you get fed and watered well in PE.

You don't need a visa but you do need to apply for ESTA, which is the visa waiver programme. You need to get this at least 72 hours before you travel. There will be no form filling (if you remember the old green I-94W forms for landing in the US) as this is linked to your ESTA/passport now.

If you transited via the US when you travelled out here, you may be asked when you last visited the US - the transit counts! We were nearly caught out with this when we flew into LA last year for a visit. The immigration agent asked when our last visit was and we said we'd left the US on the 17 Sept 2010. We'd actually flown to London on that day, then flew back and transited via LA on our way to NZ on the 18 Sept (long story - but it cost us about 1/3 less that way!). Our transit time still counted as a "visit" so our insistence that our last stay ended on 17 Sept nearly got us in trouble!